This Bronze alloy contains 5% nickel for mechanical stability, resistance to wear and hardness, and the copper for it’s ability to conduct heat.

Up to 25% of the heat of the valve is transferred from the stem to the guide and then through the head. It also prevents valve guide seizing and a longer guide life.

Why Ampco 45 Copper Valve Seats?

Ampco 45 copper seats consist of 80% copper and 5% nickel. The copper absorbs the heat from the valve 3 times better and faster than the standard powdered iron seats, the only time the valve can cool down is when it is on the valve seat.

The nickel content stabilises the seat and gives it enough hardnaes to keep it from pounding out.

Why Not OEM Iron Seats?

Powdered iron seats as used in most motor cylce heads don’t have the custioning effect that the Ampco 45 seat has on the titanium valve. It works hardens, that is why sometimes you will get 20 hours out of the first set of valves and 5 hours out of the second set and a couple of rides out of the third. THe seats will get that hard that widening the seat face or as some people call it diamond lapping the seat will not prevent the inevitable

What is Port and Polish?

Often mis-used term. Back in the early days, a port was ground as large as you could get it and then polished to a mirror like finish with the thinking that smooth was better for air flow. It also looked pretty. When flow benches cames on the scence, it was discovered that the polishing part was actually hurting the port. The greater the air speed, the more it hurt. How can that be? – There is this thing called a boundry layer which is actually caused by the friction of the air as it makes contact with the port wall, the friction causes the air to tumble at the point of contact. Compare this to a wave reaching the bench, the closer it gets to the sand, the higher the wave gets until it collapses, only to start all over again. Now you have turbulence. Air needs a lubricant to eliminate the drag, the best lube for air is a cushion of “air”. Fine scratches perpendicular to the direction of flow acts as a tripping point for the air that contacts it. The air tumbles at every scratch forming what is called a “boundry layer” thats about the same size high as the scatch is deep. The air flowing in the port uses this boundry layer as it’s cushion or lube therefor is more resistant to turbulence, you can demonstrate this to yourself by pushing your finger over mildly abraded surface and then a piece of glass.

So after all that, the term “ported and polished” has stuck with us even through “polishing” hasn’t been done for over 20 years.